Pulsed laser deposition of ferroelectric multilayer capacitors by YBa₂Cu₃O_7-δ/BaTiO₃/YBa₂Cu₃ O_7-δ on Si(100) substrates

Ferroelectric multilayer capacitors (YBCO/BTO/YBCO) are fabricated on YSZ buffered Si (100) substrates by using pulsed-laser deposition technique. The deposition process is monitored in situ by using a Fourier Transform Infrared Spectrometer (FTIR), which measures the film's deposition rate and dielectric constant during the growth process. All four oxide layers in such a multilayer capacitor are grown in situ without breaking the vacuum, and without lowering the substrate temperature to below 600 °C. The electrical properties and microstructures of the multilayer capacitor are studied and the optimal deposition condition are identified. Sharp resistive transitions are achieved for both the top and the bottom YBCO layers with on-sets at 90 K, zero resistance at 89 K for the bottom layer and 88 K for the top layer. X-ray diffraction θ-2θ and Φ scans indicate that all four deposited oxide layers have their c-axis perpendicular to the substrate, and have less that 10% in-plane misorientation. The dielectric constant of the BTO layer is over 210. Hysteresis P-E characteristics and current-voltage curves are also measured to determine dielectric properties of the barium titanate films. Preliminary results with LaSrCoO (LSCO) electrode layer are also presented.